Let's do some math ..  Rounding examples of 7 random hypothetical purchases:
Case	Tag   Price	Sales   Tax %	Raw Total   Incl. Sales Tax	Rounded   to Penny	Rounded   to Nickel	Rounded   to Dime
Purchase #1	$176.78	11.363%	$196.8675	$196.87	$196.85	$196.90
Purchase #2	$58.44	8.646%	$63.4927	$63.49	$63.50	$63.50
Purchase #3	$106.65	5.122%	$112.1126	$112.11	$112.10	$112.10
Purchase #4	$154.93	10.473%	$171.1558	$171.16	$171.15	$171.20
Purchase #5	$31.76	6.474%	$33.8161	$33.82	$33.80	$33.80
Purchase #6	$144.74	9.628%	$158.6756	$158.68	$158.70	$158.70
Purchase #7	$133.78	10.397%	$147.6891	$147.69	$147.70	$147.70
7 purchase totals =	$807.08		$883.8094	$883.82	$883.80	$883.90